Coolant leak

[peterllo]

My '95 leaks coolant, I recently bought the car, the coolant was low when we checked the car but we could not find a source. The sellers records indicate that the radiator, pump and hoses were all replaced within the last two years. As part of the inspection process I naturally had my mechanic replace soft hoses and refill with a clean mix.

I topped the system up and a couple of days later found a puddle in the driveway after the car had been left to warm up for 5 to 10 minutes. As close as I can tell the radiator seeps when the system is pressurized. The leaking stops when the system has lost one to two cups of coolant. The overflow bottle is fine but when you unscrew the bleed cap you can see the level is down. The car does not overheat, temp gage goes to the middle as is should and so on. The source seems to be low on the left side below the coolant overflow tank. My question is this can a stop leak product such as Barr's Leak be added safely to these systems? Or are these radiators capable of being re-crimped to tighten them up?

The prior owner, and myself, have only used BMW or Mercedes fluid and distilled water.

[632 Regal]

if there was a puddle then it should be fairly easy to locate the leak before throwing dirt in the system.

[peterllo]

if there was a puddle then it should be fairly easy to locate the leak before throwing dirt in the system.

You would think. But all I can find are some drops on the lower, inner edge of the radiator where the aluminum is clamped to the plastic. This on the left side. Nothing is dripping from the hoses. In hunting around I came accross another guy who described a similar problem and found it to the the overflow tank's lower O-ring, so I considered this as the problem but with the upper O-ring being the culprit as the leak stop when maybe a cup or so has bled off.

By the way, nice color, mines the same.

[PatrickPGH]

Thanks

[peterllo]

Thanks

sorry 525i, M50.

[632 Regal]

Umm...look under where it says 632 Regal.

[Elekta]

All I know is, if you are paying by the hour and they have to remove many parts to get at a water pump or a cracked thermostat housing, replace it all and sleep well at night. That would include belts and any suspect pulleys.

I just replaced the thermostat housing and didn't replace the pump, and now that the housing holds fine, it caused the weep hole in the pump to leak.

If you're gonna do it, do it once

[Gooch]

Any stop leak has to be added directly into the radiator with the car warm and the thermostat open. Or you'll end up with a glob at the bottom of the radiator. You cannot add it through the overflow bottle which creates a problem with these M50's.

Before taking that step, I also had a leak in same place. Actually two different leaks. One was the seal between the overflow bottle and the radiator. The other was between the lower radiator hose and the radiator. That last one only leaked at a specific temperature under pressure.

Also agree with ealier post, if the water pump is a plastic impellor OEM, change it. It will fail and most likely on a hot day far away from home. Happened to me.

[peterllo]

As everyone comes in suggesting the O-rings I'll do that first $15 versus $60 or $81 plus labor and materials at the dealer. The radiator, pump, and 'stat are about two years old.

[philbyil]

If it is just dripping from the radiator, it could be a leaking/cracked overflow tank, hose neck or tank/radiator o ring problem. They may have replaced the radiator and kept the old tank. None of this is wildly expensive and its better simply to replace the whole unit or R&R the Orings...could have just been a bad install. Now if its from the engine side/water pump, they may have replaced the pump but not the thermostat housing! In which case you will need to install an alloy cover instead of the thermoplastic housing.